It has previously been proposed to electronically control the operation of internal combustion engines (ICEs), for example to control the ignition instant thereof, by utilizing a central microprocessor which provides an output signal precisely at the appropriate time to initiate an ignition spark, the time of initiation of the ignition spark being dependent on actual operating conditions of the ICE at that time. The referenced U.S. Pat. No. 4,084,240, Lappington, describes such a control system in which the microprocessor is connected to and associated with an electronically programmable read-only memory (EPROM). The EPROM has data stored therein which are specifically associated with the engine to be controlled, for example the specific model and type number of the engine. The control system thus will have data therein which are representative of the operating conditions or operating characteristics of one specific engine of an engine or engine type or series only. It is very difficult to adapt the program to changed operating conditions of the engine, for example operating conditions which require a different association of output data with input data representative of existing operating condition of the engine at any one period of time. To change the data in the EPROM of the system of the referenced patent, it is necessary to reprogram the entire EPROM, for example if the engine operates differently in different localities, depending, for example, on specific exhaust emission requirements or the like; the engine ages; or redesign of elements within the engine, even of a standard type or series, changes the respective operating characteristics of the engine under given operating conditions.